The goal of this project is to generate an improved HIV-1 vaccine immunogen geared toward antibody responses by engineering an HIV-1 Envelope glycoprotein (Env) trimeric complex that is stabilized in its functionally relevant conformation by application of Avatar's proprietary dityrosine protein stabilization technology. The project breaks into two Specific Aims: (i) identification of constructs in which dityrosine crosslinks form to stabilize Env complexes, and (ii) antigenic and physiochemical analyses of DT stabilized Env trimers identified in (i) above, specifically by antigenic and Biacore analyses, and amino acid, mass spectrometric, and size exclusion chromatographic analyses, respectively. The project will be executed in collaboration between Avatar Medical, LLC and the International AIDS Vaccine Initiative. IAVI will design the constructs for evaluation, and Avatar will generate the DNA constructs required for protein construct expression and evaluation. Avatar and IAVI will jointly generate and purify the protein. IAVI will conduct the antigenic analyses, and Avatar will conduct biophysical characterization, including conducting amino acid and size exclusion chromatographic analysis, and overseeing the mass spectrometric analysis outsourced to Creative Proteomics, Inc.